Coal dissolution process

ABSTRACT

Process for dissolving bituminous coal by heating a mixture of said coal, a hydrogen donor oil, carbon monoxide, water, and an alkali metal hydroxide or its precursor at a temperature of about 400*-450* C. and under a total pressure of at least about 4,000 p.s.i.g.

United States Patent Seitzer 154] COAL DISSOLUTION PROCESS [21] Appl. No.: 63,334

52 US. Cl ..208/8, 208/10 51 1111.01 ..Cl0g 1/00 [58] Field of Search ..208/10, 8

[56] References Cited UNITED STATES PATENTS 1,445,423 2/1923 Ulke ..208/8 1,838,548 12/1931 Haslam et al... ...208/8 2,034,818 3/1936 Loughrey .208/8 3,341,447 9/1967 Bull 61 al..... ...208/8 3,477,941 11/1969 Nelson ..208/8 1451 Feb. 15, 1972 Primary Examiner-De1bert E. Gantz Assistant ExaminerVeronica OKeefe Attorney-George L. Church, Donald R. Johnson, Wilmer E. McCorquodale, Jr. and Paul Lipsitz [57] ABSTRACT Process for dissolving bituminous coal by heating a mixture of said coal, a hydrogen donor oil, carbon monoxide, water, and an alkali metal hydroxide or its preoursor at a temperature of about 400-450 C. and under a total pressure of at least about 4,000 p.s.i.g.

8 Claims, No Drawings COAL DISSOLUTION PROCESS Much effort has been expended in attempting to convert coal into useful liquid fuels. A desirable approach is to liquefy the coal and subject it to the usual cracking and hydrocracking operations to provide fuel oils, gasoline, and the like. Much difficulty has been encountered, however, in the step of bringing the solid coal into liquid form so that it can be readily subjected to refinery operations and this has been particularly true with bituminous coals. Heretofore, available processes have yielded only limited solubility of bituminous coals and significant amounts of insolubles had to be removed by one means or another, all of which were expensive and decreased the efficiency of the overall process.

It has now been found that bituminous coal may readily be essentially completely solubilized by an economical highly efficient process. This is accomplished by subjecting a mixture of powdered coal, a donor solvent oil, carbon monoxide, water, and an alkali metal hydroxide (or an alkali metal hydroxide precursor) to an elevated temperature of about 400-450 C. at a pressure of at least about 4,000 p.s.i.g. In this way the coal is essentially completely solubilized and the liquid which is obtained is readily handled and subjected to normal refinery operations to provide useful liquid fuels. Coal useful in the process will be a bituminous coal and Illinois bituminous coal is particularly useful. However, other bituminous coals are also useful such as Rock Springs Wyoming coal, Utah coal, Western Pennsylvania coal, and the like.

As indicated the oil used in the process of the invention is a hydrogen donor solvent. These donor solvent materials are well known and comprise aromatic hydrocarbons which are partially hydrogenated, generally having one or more of the nuclei at least partially saturated. Several examples of such materials are tetralin. dihydronaphthalene, dihydroalkylnaphthalenes, dihydrophenanthrene, dihydroanthracene, dihydrochrysenes, tetrahydrochrysenes, tetrahydropyrenes, tetrahydrofluoranthenes and the like. Of particular value in the process of this invention as hydrogen donor solvents are the hydrophenanthrenes and hydroanthracenes such as dihydroanthracene. It will be understood that these materials may be'obtained from any source, but are readily available from coal processing systems as anthracene oil, and the like. Of particular value are recycle oils from the coal dissolving process of the invention.

The alkali hydroxides which appear to promote solution of the coal will preferably be an alkali metal hydroxide, ammonium hydroxide, or any precursor of these materials. By precursor is meant a material which under conditions of the process will be converted to an alkali and thereby serve to function in the manner of an alkali metal or ammonium hydroxide. Examples of such materials are alkali metal and ammonium salts of carbonates, acetates, nitrates, oxalates, halides (e.g., chlorides, bromides, and iodides) and the like, which under the reaction conditions are hydrolyzed to alkali metal or ammonium hydroxides. It is surprising that hydroxides such as magnesium, calcium and the like are not operable.

In carrying out the process of the invention coal is powdered and mixed with the donor solvent, which is preferably anthracene oil, recycle oil, or its equivalent. Generally the ratio of coal to oil will be from about 1:4 to about 1:1 on a weight basis with a 1 to 1 ratio being preferred. Water and the base are then added to the mixture and preferably this is added in the form of a solution of the base or precursor in water. The amount of water present should be sufficient to generate a water vapor pressure in the system of at least about one-fifth of the total pressure. Similarly, the amount of carbon monoxide will be sufficient to generate at least one-fifth of the total pressure. It will be understood that the water pressure and carbon monoxide pressure account primarily for the total pressure in the system. The mixture of coal, oil, water and base is then placed in a pressure vessel and pressured with carbon monoxide to the desired pressure and the contents of the pressure vessel heated to a temperature of about 400450 C. Total pressure generated will be between about 4,000 and about 6,000 p.s.i.g. Dissolution of the coal occurs in a relative- 1y short time, being on the order of about 0.5 to about 3 hours, and solution is essentially complete with very little if any insoluble material being present. Liquefied coal produced by the method of the invention is then subjected to normal cracking and hydrocracking reactions to obtain a liquid fuel such as gasoline, fuel oil, kerosene and the like.

The following examples will serve to further illustrate the invention:

EXAMPLE 1 A 1 liter rocking autoclave was charged with 75 g. of powdered bituminous coal (Illinois No. 6) and 75 g. of anthracene oil and then 75 g. of water containing 2.5 g. of NH OH. This represents 3.2 percent of NI-I OH based on the coal charged. The reactor was sealed, pressure tested, and then pressured with carbon monoxide to 1,200 p.s.i.g. The reactor was heated to 415 C. for one hour, allowed to cool, and the product then filtered to remove the solids which were washed with a toluene acetone mixture, dried, and weighed. The percent of organic solids undissolved was 14 percent whereas 33 percent was undissolved when the run was repeated without the ammonium hydroxide.

EXAMPLE 2 Following the details and procedure of Example 1, runs were made with various alkali metal hydroxides. The following Table I indicates the results obtained:

TABLE I Percent Alkali Hydroxide Max. Ci Undissulvcd (Based On Coal Charged) Pressure Organic Solids None 5,800 33 2% NaOH 5,800 10 3% NaOH 5,l00 5 2% KOH 4,800 0 2% LiOH 4,700 It) EXAMPLE 3 The process of Example 1 was repeated with various precursors of alkali metal hydroxides with the results shown in Table II.

When the process of Example 1 is repeated with 3 percent magnesium acetate and 7 percent calcium acetate, the maximum pressure being 4,800 p.s.i.g., the amount of undissolved organic solids is 30 percent and 20 percent respectively, thus showing the high specificity of the process for alkali metal hydroxides.

The invention claimed is:

1. A process for dissolving bituminous coal which comprises heating at about 400 C. to about 450 C. under a total pressure of at least about 4,000 p.s.i.g., a mixture of said finely di- 5. The process of claim 4 where the promoter is potassium oxalate.

6. The process of claim 1 where the promoter is an alkali metal acetate.

7. The process of claim 1 where the oil is recycle oil and the promoter is sodium acetate.

8. The process of claim 1 where the oil is recycle oil and the promoter is an alkali metal nitrate. 

2. The process of claim 1 where the coal is an Illinois No. 6 coal, the oil is anthracene oil and the promoter is an alkali metal carbonate.
 3. The process of claim 1 where the oil is a recycle oil and the promoter is sodium carbonate.
 4. The process of claim 1 where the oil is a recycle oil and the promoter is an alkali metal oxalate.
 5. The process of claim 4 where the promoter is potassium oxalate.
 6. The process of claim 1 where the promoter is an alkali metal acetate.
 7. The process of claim 1 where the oil is recycle oil and the promoter is sodium acetate.
 8. The process of claim 1 where the oil is recycle oil and the promoter is an alkali metal nitrate. 